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-rw-r--r--block/blk-mq.c1480
1 files changed, 1480 insertions, 0 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c
new file mode 100644
index 000000000000..f21ec964e411
--- /dev/null
+++ b/block/blk-mq.c
@@ -0,0 +1,1480 @@
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/backing-dev.h>
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/mm.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+#include <linux/smp.h>
+#include <linux/llist.h>
+#include <linux/list_sort.h>
+#include <linux/cpu.h>
+#include <linux/cache.h>
+#include <linux/sched/sysctl.h>
+#include <linux/delay.h>
+
+#include <trace/events/block.h>
+
+#include <linux/blk-mq.h>
+#include "blk.h"
+#include "blk-mq.h"
+#include "blk-mq-tag.h"
+
+static DEFINE_MUTEX(all_q_mutex);
+static LIST_HEAD(all_q_list);
+
+static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx);
+
+DEFINE_PER_CPU(struct llist_head, ipi_lists);
+
+static struct blk_mq_ctx *__blk_mq_get_ctx(struct request_queue *q,
+ unsigned int cpu)
+{
+ return per_cpu_ptr(q->queue_ctx, cpu);
+}
+
+/*
+ * This assumes per-cpu software queueing queues. They could be per-node
+ * as well, for instance. For now this is hardcoded as-is. Note that we don't
+ * care about preemption, since we know the ctx's are persistent. This does
+ * mean that we can't rely on ctx always matching the currently running CPU.
+ */
+static struct blk_mq_ctx *blk_mq_get_ctx(struct request_queue *q)
+{
+ return __blk_mq_get_ctx(q, get_cpu());
+}
+
+static void blk_mq_put_ctx(struct blk_mq_ctx *ctx)
+{
+ put_cpu();
+}
+
+/*
+ * Check if any of the ctx's have pending work in this hardware queue
+ */
+static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
+{
+ unsigned int i;
+
+ for (i = 0; i < hctx->nr_ctx_map; i++)
+ if (hctx->ctx_map[i])
+ return true;
+
+ return false;
+}
+
+/*
+ * Mark this ctx as having pending work in this hardware queue
+ */
+static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
+ struct blk_mq_ctx *ctx)
+{
+ if (!test_bit(ctx->index_hw, hctx->ctx_map))
+ set_bit(ctx->index_hw, hctx->ctx_map);
+}
+
+static struct request *blk_mq_alloc_rq(struct blk_mq_hw_ctx *hctx, gfp_t gfp,
+ bool reserved)
+{
+ struct request *rq;
+ unsigned int tag;
+
+ tag = blk_mq_get_tag(hctx->tags, gfp, reserved);
+ if (tag != BLK_MQ_TAG_FAIL) {
+ rq = hctx->rqs[tag];
+ rq->tag = tag;
+
+ return rq;
+ }
+
+ return NULL;
+}
+
+static int blk_mq_queue_enter(struct request_queue *q)
+{
+ int ret;
+
+ __percpu_counter_add(&q->mq_usage_counter, 1, 1000000);
+ smp_wmb();
+ /* we have problems to freeze the queue if it's initializing */
+ if (!blk_queue_bypass(q) || !blk_queue_init_done(q))
+ return 0;
+
+ __percpu_counter_add(&q->mq_usage_counter, -1, 1000000);
+
+ spin_lock_irq(q->queue_lock);
+ ret = wait_event_interruptible_lock_irq(q->mq_freeze_wq,
+ !blk_queue_bypass(q), *q->queue_lock);
+ /* inc usage with lock hold to avoid freeze_queue runs here */
+ if (!ret)
+ __percpu_counter_add(&q->mq_usage_counter, 1, 1000000);
+ spin_unlock_irq(q->queue_lock);
+
+ return ret;
+}
+
+static void blk_mq_queue_exit(struct request_queue *q)
+{
+ __percpu_counter_add(&q->mq_usage_counter, -1, 1000000);
+}
+
+/*
+ * Guarantee no request is in use, so we can change any data structure of
+ * the queue afterward.
+ */
+static void blk_mq_freeze_queue(struct request_queue *q)
+{
+ bool drain;
+
+ spin_lock_irq(q->queue_lock);
+ drain = !q->bypass_depth++;
+ queue_flag_set(QUEUE_FLAG_BYPASS, q);
+ spin_unlock_irq(q->queue_lock);
+
+ if (!drain)
+ return;
+
+ while (true) {
+ s64 count;
+
+ spin_lock_irq(q->queue_lock);
+ count = percpu_counter_sum(&q->mq_usage_counter);
+ spin_unlock_irq(q->queue_lock);
+
+ if (count == 0)
+ break;
+ blk_mq_run_queues(q, false);
+ msleep(10);
+ }
+}
+
+static void blk_mq_unfreeze_queue(struct request_queue *q)
+{
+ bool wake = false;
+
+ spin_lock_irq(q->queue_lock);
+ if (!--q->bypass_depth) {
+ queue_flag_clear(QUEUE_FLAG_BYPASS, q);
+ wake = true;
+ }
+ WARN_ON_ONCE(q->bypass_depth < 0);
+ spin_unlock_irq(q->queue_lock);
+ if (wake)
+ wake_up_all(&q->mq_freeze_wq);
+}
+
+bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
+{
+ return blk_mq_has_free_tags(hctx->tags);
+}
+EXPORT_SYMBOL(blk_mq_can_queue);
+
+static void blk_mq_rq_ctx_init(struct blk_mq_ctx *ctx, struct request *rq,
+ unsigned int rw_flags)
+{
+ rq->mq_ctx = ctx;
+ rq->cmd_flags = rw_flags;
+ ctx->rq_dispatched[rw_is_sync(rw_flags)]++;
+}
+
+static struct request *__blk_mq_alloc_request(struct blk_mq_hw_ctx *hctx,
+ gfp_t gfp, bool reserved)
+{
+ return blk_mq_alloc_rq(hctx, gfp, reserved);
+}
+
+static struct request *blk_mq_alloc_request_pinned(struct request_queue *q,
+ int rw, gfp_t gfp,
+ bool reserved)
+{
+ struct request *rq;
+
+ do {
+ struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
+ struct blk_mq_hw_ctx *hctx = q->mq_ops->map_queue(q, ctx->cpu);
+
+ rq = __blk_mq_alloc_request(hctx, gfp & ~__GFP_WAIT, reserved);
+ if (rq) {
+ blk_mq_rq_ctx_init(ctx, rq, rw);
+ break;
+ } else if (!(gfp & __GFP_WAIT))
+ break;
+
+ blk_mq_put_ctx(ctx);
+ __blk_mq_run_hw_queue(hctx);
+ blk_mq_wait_for_tags(hctx->tags);
+ } while (1);
+
+ return rq;
+}
+
+struct request *blk_mq_alloc_request(struct request_queue *q, int rw, gfp_t gfp)
+{
+ struct request *rq;
+
+ if (blk_mq_queue_enter(q))
+ return NULL;
+
+ rq = blk_mq_alloc_request_pinned(q, rw, gfp, false);
+ blk_mq_put_ctx(rq->mq_ctx);
+ return rq;
+}
+
+struct request *blk_mq_alloc_reserved_request(struct request_queue *q, int rw,
+ gfp_t gfp)
+{
+ struct request *rq;
+
+ if (blk_mq_queue_enter(q))
+ return NULL;
+
+ rq = blk_mq_alloc_request_pinned(q, rw, gfp, true);
+ blk_mq_put_ctx(rq->mq_ctx);
+ return rq;
+}
+EXPORT_SYMBOL(blk_mq_alloc_reserved_request);
+
+/*
+ * Re-init and set pdu, if we have it
+ */
+static void blk_mq_rq_init(struct blk_mq_hw_ctx *hctx, struct request *rq)
+{
+ blk_rq_init(hctx->queue, rq);
+
+ if (hctx->cmd_size)
+ rq->special = blk_mq_rq_to_pdu(rq);
+}
+
+static void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx,
+ struct blk_mq_ctx *ctx, struct request *rq)
+{
+ const int tag = rq->tag;
+ struct request_queue *q = rq->q;
+
+ blk_mq_rq_init(hctx, rq);
+ blk_mq_put_tag(hctx->tags, tag);
+
+ blk_mq_queue_exit(q);
+}
+
+void blk_mq_free_request(struct request *rq)
+{
+ struct blk_mq_ctx *ctx = rq->mq_ctx;
+ struct blk_mq_hw_ctx *hctx;
+ struct request_queue *q = rq->q;
+
+ ctx->rq_completed[rq_is_sync(rq)]++;
+
+ hctx = q->mq_ops->map_queue(q, ctx->cpu);
+ __blk_mq_free_request(hctx, ctx, rq);
+}
+
+static void blk_mq_bio_endio(struct request *rq, struct bio *bio, int error)
+{
+ if (error)
+ clear_bit(BIO_UPTODATE, &bio->bi_flags);
+ else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
+ error = -EIO;
+
+ if (unlikely(rq->cmd_flags & REQ_QUIET))
+ set_bit(BIO_QUIET, &bio->bi_flags);
+
+ /* don't actually finish bio if it's part of flush sequence */
+ if (!(rq->cmd_flags & REQ_FLUSH_SEQ))
+ bio_endio(bio, error);
+}
+
+void blk_mq_complete_request(struct request *rq, int error)
+{
+ struct bio *bio = rq->bio;
+ unsigned int bytes = 0;
+
+ trace_block_rq_complete(rq->q, rq);
+
+ while (bio) {
+ struct bio *next = bio->bi_next;
+
+ bio->bi_next = NULL;
+ bytes += bio->bi_size;
+ blk_mq_bio_endio(rq, bio, error);
+ bio = next;
+ }
+
+ blk_account_io_completion(rq, bytes);
+
+ if (rq->end_io)
+ rq->end_io(rq, error);
+ else
+ blk_mq_free_request(rq);
+
+ blk_account_io_done(rq);
+}
+
+void __blk_mq_end_io(struct request *rq, int error)
+{
+ if (!blk_mark_rq_complete(rq))
+ blk_mq_complete_request(rq, error);
+}
+
+#if defined(CONFIG_SMP) && defined(CONFIG_USE_GENERIC_SMP_HELPERS)
+
+/*
+ * Called with interrupts disabled.
+ */
+static void ipi_end_io(void *data)
+{
+ struct llist_head *list = &per_cpu(ipi_lists, smp_processor_id());
+ struct llist_node *entry, *next;
+ struct request *rq;
+
+ entry = llist_del_all(list);
+
+ while (entry) {
+ next = entry->next;
+ rq = llist_entry(entry, struct request, ll_list);
+ __blk_mq_end_io(rq, rq->errors);
+ entry = next;
+ }
+}
+
+static int ipi_remote_cpu(struct blk_mq_ctx *ctx, const int cpu,
+ struct request *rq, const int error)
+{
+ struct call_single_data *data = &rq->csd;
+
+ rq->errors = error;
+ rq->ll_list.next = NULL;
+
+ /*
+ * If the list is non-empty, an existing IPI must already
+ * be "in flight". If that is the case, we need not schedule
+ * a new one.
+ */
+ if (llist_add(&rq->ll_list, &per_cpu(ipi_lists, ctx->cpu))) {
+ data->func = ipi_end_io;
+ data->flags = 0;
+ __smp_call_function_single(ctx->cpu, data, 0);
+ }
+
+ return true;
+}
+#else /* CONFIG_SMP && CONFIG_USE_GENERIC_SMP_HELPERS */
+static int ipi_remote_cpu(struct blk_mq_ctx *ctx, const int cpu,
+ struct request *rq, const int error)
+{
+ return false;
+}
+#endif
+
+/*
+ * End IO on this request on a multiqueue enabled driver. We'll either do
+ * it directly inline, or punt to a local IPI handler on the matching
+ * remote CPU.
+ */
+void blk_mq_end_io(struct request *rq, int error)
+{
+ struct blk_mq_ctx *ctx = rq->mq_ctx;
+ int cpu;
+
+ if (!ctx->ipi_redirect)
+ return __blk_mq_end_io(rq, error);
+
+ cpu = get_cpu();
+
+ if (cpu == ctx->cpu || !cpu_online(ctx->cpu) ||
+ !ipi_remote_cpu(ctx, cpu, rq, error))
+ __blk_mq_end_io(rq, error);
+
+ put_cpu();
+}
+EXPORT_SYMBOL(blk_mq_end_io);
+
+static void blk_mq_start_request(struct request *rq)
+{
+ struct request_queue *q = rq->q;
+
+ trace_block_rq_issue(q, rq);
+
+ /*
+ * Just mark start time and set the started bit. Due to memory
+ * ordering, we know we'll see the correct deadline as long as
+ * REQ_ATOMIC_STARTED is seen.
+ */
+ rq->deadline = jiffies + q->rq_timeout;
+ set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
+}
+
+static void blk_mq_requeue_request(struct request *rq)
+{
+ struct request_queue *q = rq->q;
+
+ trace_block_rq_requeue(q, rq);
+ clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
+}
+
+struct blk_mq_timeout_data {
+ struct blk_mq_hw_ctx *hctx;
+ unsigned long *next;
+ unsigned int *next_set;
+};
+
+static void blk_mq_timeout_check(void *__data, unsigned long *free_tags)
+{
+ struct blk_mq_timeout_data *data = __data;
+ struct blk_mq_hw_ctx *hctx = data->hctx;
+ unsigned int tag;
+
+ /* It may not be in flight yet (this is where
+ * the REQ_ATOMIC_STARTED flag comes in). The requests are
+ * statically allocated, so we know it's always safe to access the
+ * memory associated with a bit offset into ->rqs[].
+ */
+ tag = 0;
+ do {
+ struct request *rq;
+
+ tag = find_next_zero_bit(free_tags, hctx->queue_depth, tag);
+ if (tag >= hctx->queue_depth)
+ break;
+
+ rq = hctx->rqs[tag++];
+
+ if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
+ continue;
+
+ blk_rq_check_expired(rq, data->next, data->next_set);
+ } while (1);
+}
+
+static void blk_mq_hw_ctx_check_timeout(struct blk_mq_hw_ctx *hctx,
+ unsigned long *next,
+ unsigned int *next_set)
+{
+ struct blk_mq_timeout_data data = {
+ .hctx = hctx,
+ .next = next,
+ .next_set = next_set,
+ };
+
+ /*
+ * Ask the tagging code to iterate busy requests, so we can
+ * check them for timeout.
+ */
+ blk_mq_tag_busy_iter(hctx->tags, blk_mq_timeout_check, &data);
+}
+
+static void blk_mq_rq_timer(unsigned long data)
+{
+ struct request_queue *q = (struct request_queue *) data;
+ struct blk_mq_hw_ctx *hctx;
+ unsigned long next = 0;
+ int i, next_set = 0;
+
+ queue_for_each_hw_ctx(q, hctx, i)
+ blk_mq_hw_ctx_check_timeout(hctx, &next, &next_set);
+
+ if (next_set)
+ mod_timer(&q->timeout, round_jiffies_up(next));
+}
+
+/*
+ * Reverse check our software queue for entries that we could potentially
+ * merge with. Currently includes a hand-wavy stop count of 8, to not spend
+ * too much time checking for merges.
+ */
+static bool blk_mq_attempt_merge(struct request_queue *q,
+ struct blk_mq_ctx *ctx, struct bio *bio)
+{
+ struct request *rq;
+ int checked = 8;
+
+ list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
+ int el_ret;
+
+ if (!checked--)
+ break;
+
+ if (!blk_rq_merge_ok(rq, bio))
+ continue;
+
+ el_ret = blk_try_merge(rq, bio);
+ if (el_ret == ELEVATOR_BACK_MERGE) {
+ if (bio_attempt_back_merge(q, rq, bio)) {
+ ctx->rq_merged++;
+ return true;
+ }
+ break;
+ } else if (el_ret == ELEVATOR_FRONT_MERGE) {
+ if (bio_attempt_front_merge(q, rq, bio)) {
+ ctx->rq_merged++;
+ return true;
+ }
+ break;
+ }
+ }
+
+ return false;
+}
+
+void blk_mq_add_timer(struct request *rq)
+{
+ __blk_add_timer(rq, NULL);
+}
+
+/*
+ * Run this hardware queue, pulling any software queues mapped to it in.
+ * Note that this function currently has various problems around ordering
+ * of IO. In particular, we'd like FIFO behaviour on handling existing
+ * items on the hctx->dispatch list. Ignore that for now.
+ */
+static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
+{
+ struct request_queue *q = hctx->queue;
+ struct blk_mq_ctx *ctx;
+ struct request *rq;
+ LIST_HEAD(rq_list);
+ int bit, queued;
+
+ if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->flags)))
+ return;
+
+ hctx->run++;
+
+ /*
+ * Touch any software queue that has pending entries.
+ */
+ for_each_set_bit(bit, hctx->ctx_map, hctx->nr_ctx) {
+ clear_bit(bit, hctx->ctx_map);
+ ctx = hctx->ctxs[bit];
+ BUG_ON(bit != ctx->index_hw);
+
+ spin_lock(&ctx->lock);
+ list_splice_tail_init(&ctx->rq_list, &rq_list);
+ spin_unlock(&ctx->lock);
+ }
+
+ /*
+ * If we have previous entries on our dispatch list, grab them
+ * and stuff them at the front for more fair dispatch.
+ */
+ if (!list_empty_careful(&hctx->dispatch)) {
+ spin_lock(&hctx->lock);
+ if (!list_empty(&hctx->dispatch))
+ list_splice_init(&hctx->dispatch, &rq_list);
+ spin_unlock(&hctx->lock);
+ }
+
+ /*
+ * Delete and return all entries from our dispatch list
+ */
+ queued = 0;
+
+ /*
+ * Now process all the entries, sending them to the driver.
+ */
+ while (!list_empty(&rq_list)) {
+ int ret;
+
+ rq = list_first_entry(&rq_list, struct request, queuelist);
+ list_del_init(&rq->queuelist);
+ blk_mq_start_request(rq);
+
+ /*
+ * Last request in the series. Flag it as such, this
+ * enables drivers to know when IO should be kicked off,
+ * if they don't do it on a per-request basis.
+ *
+ * Note: the flag isn't the only condition drivers
+ * should do kick off. If drive is busy, the last
+ * request might not have the bit set.
+ */
+ if (list_empty(&rq_list))
+ rq->cmd_flags |= REQ_END;
+
+ ret = q->mq_ops->queue_rq(hctx, rq);
+ switch (ret) {
+ case BLK_MQ_RQ_QUEUE_OK:
+ queued++;
+ continue;
+ case BLK_MQ_RQ_QUEUE_BUSY:
+ /*
+ * FIXME: we should have a mechanism to stop the queue
+ * like blk_stop_queue, otherwise we will waste cpu
+ * time
+ */
+ list_add(&rq->queuelist, &rq_list);
+ blk_mq_requeue_request(rq);
+ break;
+ default:
+ pr_err("blk-mq: bad return on queue: %d\n", ret);
+ rq->errors = -EIO;
+ case BLK_MQ_RQ_QUEUE_ERROR:
+ blk_mq_end_io(rq, rq->errors);
+ break;
+ }
+
+ if (ret == BLK_MQ_RQ_QUEUE_BUSY)
+ break;
+ }
+
+ if (!queued)
+ hctx->dispatched[0]++;
+ else if (queued < (1 << (BLK_MQ_MAX_DISPATCH_ORDER - 1)))
+ hctx->dispatched[ilog2(queued) + 1]++;
+
+ /*
+ * Any items that need requeuing? Stuff them into hctx->dispatch,
+ * that is where we will continue on next queue run.
+ */
+ if (!list_empty(&rq_list)) {
+ spin_lock(&hctx->lock);
+ list_splice(&rq_list, &hctx->dispatch);
+ spin_unlock(&hctx->lock);
+ }
+}
+
+void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
+{
+ if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->flags)))
+ return;
+
+ if (!async)
+ __blk_mq_run_hw_queue(hctx);
+ else {
+ struct request_queue *q = hctx->queue;
+
+ kblockd_schedule_delayed_work(q, &hctx->delayed_work, 0);
+ }
+}
+
+void blk_mq_run_queues(struct request_queue *q, bool async)
+{
+ struct blk_mq_hw_ctx *hctx;
+ int i;
+
+ queue_for_each_hw_ctx(q, hctx, i) {
+ if ((!blk_mq_hctx_has_pending(hctx) &&
+ list_empty_careful(&hctx->dispatch)) ||
+ test_bit(BLK_MQ_S_STOPPED, &hctx->flags))
+ continue;
+
+ blk_mq_run_hw_queue(hctx, async);
+ }
+}
+EXPORT_SYMBOL(blk_mq_run_queues);
+
+void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
+{
+ cancel_delayed_work(&hctx->delayed_work);
+ set_bit(BLK_MQ_S_STOPPED, &hctx->state);
+}
+EXPORT_SYMBOL(blk_mq_stop_hw_queue);
+
+void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
+{
+ clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
+ __blk_mq_run_hw_queue(hctx);
+}
+EXPORT_SYMBOL(blk_mq_start_hw_queue);
+
+void blk_mq_start_stopped_hw_queues(struct request_queue *q)
+{
+ struct blk_mq_hw_ctx *hctx;
+ int i;
+
+ queue_for_each_hw_ctx(q, hctx, i) {
+ if (!test_bit(BLK_MQ_S_STOPPED, &hctx->state))
+ continue;
+
+ clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
+ blk_mq_run_hw_queue(hctx, true);
+ }
+}
+EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
+
+static void blk_mq_work_fn(struct work_struct *work)
+{
+ struct blk_mq_hw_ctx *hctx;
+
+ hctx = container_of(work, struct blk_mq_hw_ctx, delayed_work.work);
+ __blk_mq_run_hw_queue(hctx);
+}
+
+static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
+ struct request *rq)
+{
+ struct blk_mq_ctx *ctx = rq->mq_ctx;
+
+ list_add_tail(&rq->queuelist, &ctx->rq_list);
+ blk_mq_hctx_mark_pending(hctx, ctx);
+
+ /*
+ * We do this early, to ensure we are on the right CPU.
+ */
+ blk_mq_add_timer(rq);
+}
+
+void blk_mq_insert_request(struct request_queue *q, struct request *rq,
+ bool run_queue)
+{
+ struct blk_mq_hw_ctx *hctx;
+ struct blk_mq_ctx *ctx, *current_ctx;
+
+ ctx = rq->mq_ctx;
+ hctx = q->mq_ops->map_queue(q, ctx->cpu);
+
+ if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
+ blk_insert_flush(rq);
+ } else {
+ current_ctx = blk_mq_get_ctx(q);
+
+ if (!cpu_online(ctx->cpu)) {
+ ctx = current_ctx;
+ hctx = q->mq_ops->map_queue(q, ctx->cpu);
+ rq->mq_ctx = ctx;
+ }
+ spin_lock(&ctx->lock);
+ __blk_mq_insert_request(hctx, rq);
+ spin_unlock(&ctx->lock);
+
+ blk_mq_put_ctx(current_ctx);
+ }
+
+ if (run_queue)
+ __blk_mq_run_hw_queue(hctx);
+}
+EXPORT_SYMBOL(blk_mq_insert_request);
+
+/*
+ * This is a special version of blk_mq_insert_request to bypass FLUSH request
+ * check. Should only be used internally.
+ */
+void blk_mq_run_request(struct request *rq, bool run_queue, bool async)
+{
+ struct request_queue *q = rq->q;
+ struct blk_mq_hw_ctx *hctx;
+ struct blk_mq_ctx *ctx, *current_ctx;
+
+ current_ctx = blk_mq_get_ctx(q);
+
+ ctx = rq->mq_ctx;
+ if (!cpu_online(ctx->cpu)) {
+ ctx = current_ctx;
+ rq->mq_ctx = ctx;
+ }
+ hctx = q->mq_ops->map_queue(q, ctx->cpu);
+
+ /* ctx->cpu might be offline */
+ spin_lock(&ctx->lock);
+ __blk_mq_insert_request(hctx, rq);
+ spin_unlock(&ctx->lock);
+
+ blk_mq_put_ctx(current_ctx);
+
+ if (run_queue)
+ blk_mq_run_hw_queue(hctx, async);
+}
+
+static void blk_mq_insert_requests(struct request_queue *q,
+ struct blk_mq_ctx *ctx,
+ struct list_head *list,
+ int depth,
+ bool from_schedule)
+
+{
+ struct blk_mq_hw_ctx *hctx;
+ struct blk_mq_ctx *current_ctx;
+
+ trace_block_unplug(q, depth, !from_schedule);
+
+ current_ctx = blk_mq_get_ctx(q);
+
+ if (!cpu_online(ctx->cpu))
+ ctx = current_ctx;
+ hctx = q->mq_ops->map_queue(q, ctx->cpu);
+
+ /*
+ * preemption doesn't flush plug list, so it's possible ctx->cpu is
+ * offline now
+ */
+ spin_lock(&ctx->lock);
+ while (!list_empty(list)) {
+ struct request *rq;
+
+ rq = list_first_entry(list, struct request, queuelist);
+ list_del_init(&rq->queuelist);
+ rq->mq_ctx = ctx;
+ __blk_mq_insert_request(hctx, rq);
+ }
+ spin_unlock(&ctx->lock);
+
+ blk_mq_put_ctx(current_ctx);
+
+ blk_mq_run_hw_queue(hctx, from_schedule);
+}
+
+static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
+{
+ struct request *rqa = container_of(a, struct request, queuelist);
+ struct request *rqb = container_of(b, struct request, queuelist);
+
+ return !(rqa->mq_ctx < rqb->mq_ctx ||
+ (rqa->mq_ctx == rqb->mq_ctx &&
+ blk_rq_pos(rqa) < blk_rq_pos(rqb)));
+}
+
+void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
+{
+ struct blk_mq_ctx *this_ctx;
+ struct request_queue *this_q;
+ struct request *rq;
+ LIST_HEAD(list);
+ LIST_HEAD(ctx_list);
+ unsigned int depth;
+
+ list_splice_init(&plug->mq_list, &list);
+
+ list_sort(NULL, &list, plug_ctx_cmp);
+
+ this_q = NULL;
+ this_ctx = NULL;
+ depth = 0;
+
+ while (!list_empty(&list)) {
+ rq = list_entry_rq(list.next);
+ list_del_init(&rq->queuelist);
+ BUG_ON(!rq->q);
+ if (rq->mq_ctx != this_ctx) {
+ if (this_ctx) {
+ blk_mq_insert_requests(this_q, this_ctx,
+ &ctx_list, depth,
+ from_schedule);
+ }
+
+ this_ctx = rq->mq_ctx;
+ this_q = rq->q;
+ depth = 0;
+ }
+
+ depth++;
+ list_add_tail(&rq->queuelist, &ctx_list);
+ }
+
+ /*
+ * If 'this_ctx' is set, we know we have entries to complete
+ * on 'ctx_list'. Do those.
+ */
+ if (this_ctx) {
+ blk_mq_insert_requests(this_q, this_ctx, &ctx_list, depth,
+ from_schedule);
+ }
+}
+
+static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
+{
+ init_request_from_bio(rq, bio);
+ blk_account_io_start(rq, 1);
+}
+
+static void blk_mq_make_request(struct request_queue *q, struct bio *bio)
+{
+ struct blk_mq_hw_ctx *hctx;
+ struct blk_mq_ctx *ctx;
+ const int is_sync = rw_is_sync(bio->bi_rw);
+ const int is_flush_fua = bio->bi_rw & (REQ_FLUSH | REQ_FUA);
+ int rw = bio_data_dir(bio);
+ struct request *rq;
+ unsigned int use_plug, request_count = 0;
+
+ /*
+ * If we have multiple hardware queues, just go directly to
+ * one of those for sync IO.
+ */
+ use_plug = !is_flush_fua && ((q->nr_hw_queues == 1) || !is_sync);
+
+ blk_queue_bounce(q, &bio);
+
+ if (use_plug && blk_attempt_plug_merge(q, bio, &request_count))
+ return;
+
+ if (blk_mq_queue_enter(q)) {
+ bio_endio(bio, -EIO);
+ return;
+ }
+
+ ctx = blk_mq_get_ctx(q);
+ hctx = q->mq_ops->map_queue(q, ctx->cpu);
+
+ trace_block_getrq(q, bio, rw);
+ rq = __blk_mq_alloc_request(hctx, GFP_ATOMIC, false);
+ if (likely(rq))
+ blk_mq_rq_ctx_init(ctx, rq, rw);
+ else {
+ blk_mq_put_ctx(ctx);
+ trace_block_sleeprq(q, bio, rw);
+ rq = blk_mq_alloc_request_pinned(q, rw, __GFP_WAIT|GFP_ATOMIC,
+ false);
+ ctx = rq->mq_ctx;
+ hctx = q->mq_ops->map_queue(q, ctx->cpu);
+ }
+
+ hctx->queued++;
+
+ if (unlikely(is_flush_fua)) {
+ blk_mq_bio_to_request(rq, bio);
+ blk_mq_put_ctx(ctx);
+ blk_insert_flush(rq);
+ goto run_queue;
+ }
+
+ /*
+ * A task plug currently exists. Since this is completely lockless,
+ * utilize that to temporarily store requests until the task is
+ * either done or scheduled away.
+ */
+ if (use_plug) {
+ struct blk_plug *plug = current->plug;
+
+ if (plug) {
+ blk_mq_bio_to_request(rq, bio);
+ if (list_empty(&plug->list))
+ trace_block_plug(q);
+ else if (request_count >= BLK_MAX_REQUEST_COUNT) {
+ blk_flush_plug_list(plug, false);
+ trace_block_plug(q);
+ }
+ list_add_tail(&rq->queuelist, &plug->mq_list);
+ blk_mq_put_ctx(ctx);
+ return;
+ }
+ }
+
+ spin_lock(&ctx->lock);
+
+ if ((hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
+ blk_mq_attempt_merge(q, ctx, bio))
+ __blk_mq_free_request(hctx, ctx, rq);
+ else {
+ blk_mq_bio_to_request(rq, bio);
+ __blk_mq_insert_request(hctx, rq);
+ }
+
+ spin_unlock(&ctx->lock);
+ blk_mq_put_ctx(ctx);
+
+ /*
+ * For a SYNC request, send it to the hardware immediately. For an
+ * ASYNC request, just ensure that we run it later on. The latter
+ * allows for merging opportunities and more efficient dispatching.
+ */
+run_queue:
+ blk_mq_run_hw_queue(hctx, !is_sync || is_flush_fua);
+}
+
+/*
+ * Default mapping to a software queue, since we use one per CPU.
+ */
+struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *q, const int cpu)
+{
+ return q->queue_hw_ctx[q->mq_map[cpu]];
+}
+EXPORT_SYMBOL(blk_mq_map_queue);
+
+struct blk_mq_hw_ctx *blk_mq_alloc_single_hw_queue(struct blk_mq_reg *reg,
+ unsigned int hctx_index)
+{
+ return kmalloc_node(sizeof(struct blk_mq_hw_ctx),
+ GFP_KERNEL | __GFP_ZERO, reg->numa_node);
+}
+EXPORT_SYMBOL(blk_mq_alloc_single_hw_queue);
+
+void blk_mq_free_single_hw_queue(struct blk_mq_hw_ctx *hctx,
+ unsigned int hctx_index)
+{
+ kfree(hctx);
+}
+EXPORT_SYMBOL(blk_mq_free_single_hw_queue);
+
+static void blk_mq_hctx_notify(void *data, unsigned long action,
+ unsigned int cpu)
+{
+ struct blk_mq_hw_ctx *hctx = data;
+ struct blk_mq_ctx *ctx;
+ LIST_HEAD(tmp);
+
+ if (action != CPU_DEAD && action != CPU_DEAD_FROZEN)
+ return;
+
+ /*
+ * Move ctx entries to new CPU, if this one is going away.
+ */
+ ctx = __blk_mq_get_ctx(hctx->queue, cpu);
+
+ spin_lock(&ctx->lock);
+ if (!list_empty(&ctx->rq_list)) {
+ list_splice_init(&ctx->rq_list, &tmp);
+ clear_bit(ctx->index_hw, hctx->ctx_map);
+ }
+ spin_unlock(&ctx->lock);
+
+ if (list_empty(&tmp))
+ return;
+
+ ctx = blk_mq_get_ctx(hctx->queue);
+ spin_lock(&ctx->lock);
+
+ while (!list_empty(&tmp)) {
+ struct request *rq;
+
+ rq = list_first_entry(&tmp, struct request, queuelist);
+ rq->mq_ctx = ctx;
+ list_move_tail(&rq->queuelist, &ctx->rq_list);
+ }
+
+ blk_mq_hctx_mark_pending(hctx, ctx);
+
+ spin_unlock(&ctx->lock);
+ blk_mq_put_ctx(ctx);
+}
+
+static void blk_mq_init_hw_commands(struct blk_mq_hw_ctx *hctx,
+ void (*init)(void *, struct blk_mq_hw_ctx *,
+ struct request *, unsigned int),
+ void *data)
+{
+ unsigned int i;
+
+ for (i = 0; i < hctx->queue_depth; i++) {
+ struct request *rq = hctx->rqs[i];
+
+ init(data, hctx, rq, i);
+ }
+}
+
+void blk_mq_init_commands(struct request_queue *q,
+ void (*init)(void *, struct blk_mq_hw_ctx *,
+ struct request *, unsigned int),
+ void *data)
+{
+ struct blk_mq_hw_ctx *hctx;
+ unsigned int i;
+
+ queue_for_each_hw_ctx(q, hctx, i)
+ blk_mq_init_hw_commands(hctx, init, data);
+}
+EXPORT_SYMBOL(blk_mq_init_commands);
+
+static void blk_mq_free_rq_map(struct blk_mq_hw_ctx *hctx)
+{
+ struct page *page;
+
+ while (!list_empty(&hctx->page_list)) {
+ page = list_first_entry(&hctx->page_list, struct page, list);
+ list_del_init(&page->list);
+ __free_pages(page, page->private);
+ }
+
+ kfree(hctx->rqs);
+
+ if (hctx->tags)
+ blk_mq_free_tags(hctx->tags);
+}
+
+static size_t order_to_size(unsigned int order)
+{
+ size_t ret = PAGE_SIZE;
+
+ while (order--)
+ ret *= 2;
+
+ return ret;
+}
+
+static int blk_mq_init_rq_map(struct blk_mq_hw_ctx *hctx,
+ unsigned int reserved_tags, int node)
+{
+ unsigned int i, j, entries_per_page, max_order = 4;
+ size_t rq_size, left;
+
+ INIT_LIST_HEAD(&hctx->page_list);
+
+ hctx->rqs = kmalloc_node(hctx->queue_depth * sizeof(struct request *),
+ GFP_KERNEL, node);
+ if (!hctx->rqs)
+ return -ENOMEM;
+
+ /*
+ * rq_size is the size of the request plus driver payload, rounded
+ * to the cacheline size
+ */
+ rq_size = round_up(sizeof(struct request) + hctx->cmd_size,
+ cache_line_size());
+ left = rq_size * hctx->queue_depth;
+
+ for (i = 0; i < hctx->queue_depth;) {
+ int this_order = max_order;
+ struct page *page;
+ int to_do;
+ void *p;
+
+ while (left < order_to_size(this_order - 1) && this_order)
+ this_order--;
+
+ do {
+ page = alloc_pages_node(node, GFP_KERNEL, this_order);
+ if (page)
+ break;
+ if (!this_order--)
+ break;
+ if (order_to_size(this_order) < rq_size)
+ break;
+ } while (1);
+
+ if (!page)
+ break;
+
+ page->private = this_order;
+ list_add_tail(&page->list, &hctx->page_list);
+
+ p = page_address(page);
+ entries_per_page = order_to_size(this_order) / rq_size;
+ to_do = min(entries_per_page, hctx->queue_depth - i);
+ left -= to_do * rq_size;
+ for (j = 0; j < to_do; j++) {
+ hctx->rqs[i] = p;
+ blk_mq_rq_init(hctx, hctx->rqs[i]);
+ p += rq_size;
+ i++;
+ }
+ }
+
+ if (i < (reserved_tags + BLK_MQ_TAG_MIN))
+ goto err_rq_map;
+ else if (i != hctx->queue_depth) {
+ hctx->queue_depth = i;
+ pr_warn("%s: queue depth set to %u because of low memory\n",
+ __func__, i);
+ }
+
+ hctx->tags = blk_mq_init_tags(hctx->queue_depth, reserved_tags, node);
+ if (!hctx->tags) {
+err_rq_map:
+ blk_mq_free_rq_map(hctx);
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+static int blk_mq_init_hw_queues(struct request_queue *q,
+ struct blk_mq_reg *reg, void *driver_data)
+{
+ struct blk_mq_hw_ctx *hctx;
+ unsigned int i, j;
+
+ /*
+ * Initialize hardware queues
+ */
+ queue_for_each_hw_ctx(q, hctx, i) {
+ unsigned int num_maps;
+ int node;
+
+ node = hctx->numa_node;
+ if (node == NUMA_NO_NODE)
+ node = hctx->numa_node = reg->numa_node;
+
+ INIT_DELAYED_WORK(&hctx->delayed_work, blk_mq_work_fn);
+ spin_lock_init(&hctx->lock);
+ INIT_LIST_HEAD(&hctx->dispatch);
+ hctx->queue = q;
+ hctx->queue_num = i;
+ hctx->flags = reg->flags;
+ hctx->queue_depth = reg->queue_depth;
+ hctx->cmd_size = reg->cmd_size;
+
+ blk_mq_init_cpu_notifier(&hctx->cpu_notifier,
+ blk_mq_hctx_notify, hctx);
+ blk_mq_register_cpu_notifier(&hctx->cpu_notifier);
+
+ if (blk_mq_init_rq_map(hctx, reg->reserved_tags, node))
+ break;
+
+ /*
+ * Allocate space for all possible cpus to avoid allocation in
+ * runtime
+ */
+ hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
+ GFP_KERNEL, node);
+ if (!hctx->ctxs)
+ break;
+
+ num_maps = ALIGN(nr_cpu_ids, BITS_PER_LONG) / BITS_PER_LONG;
+ hctx->ctx_map = kzalloc_node(num_maps * sizeof(unsigned long),
+ GFP_KERNEL, node);
+ if (!hctx->ctx_map)
+ break;
+
+ hctx->nr_ctx_map = num_maps;
+ hctx->nr_ctx = 0;
+
+ if (reg->ops->init_hctx &&
+ reg->ops->init_hctx(hctx, driver_data, i))
+ break;
+ }
+
+ if (i == q->nr_hw_queues)
+ return 0;
+
+ /*
+ * Init failed
+ */
+ queue_for_each_hw_ctx(q, hctx, j) {
+ if (i == j)
+ break;
+
+ if (reg->ops->exit_hctx)
+ reg->ops->exit_hctx(hctx, j);
+
+ blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
+ blk_mq_free_rq_map(hctx);
+ kfree(hctx->ctxs);
+ }
+
+ return 1;
+}
+
+static void blk_mq_init_cpu_queues(struct request_queue *q,
+ unsigned int nr_hw_queues)
+{
+ unsigned int i;
+
+ for_each_possible_cpu(i) {
+ struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
+ struct blk_mq_hw_ctx *hctx;
+
+ memset(__ctx, 0, sizeof(*__ctx));
+ __ctx->cpu = i;
+ spin_lock_init(&__ctx->lock);
+ INIT_LIST_HEAD(&__ctx->rq_list);
+ __ctx->queue = q;
+
+ /* If the cpu isn't online, the cpu is mapped to first hctx */
+ hctx = q->mq_ops->map_queue(q, i);
+ hctx->nr_ctx++;
+
+ if (!cpu_online(i))
+ continue;
+
+ /*
+ * Set local node, IFF we have more than one hw queue. If
+ * not, we remain on the home node of the device
+ */
+ if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
+ hctx->numa_node = cpu_to_node(i);
+ }
+}
+
+static void blk_mq_map_swqueue(struct request_queue *q)
+{
+ unsigned int i;
+ struct blk_mq_hw_ctx *hctx;
+ struct blk_mq_ctx *ctx;
+
+ queue_for_each_hw_ctx(q, hctx, i) {
+ hctx->nr_ctx = 0;
+ }
+
+ /*
+ * Map software to hardware queues
+ */
+ queue_for_each_ctx(q, ctx, i) {
+ /* If the cpu isn't online, the cpu is mapped to first hctx */
+ hctx = q->mq_ops->map_queue(q, i);
+ ctx->index_hw = hctx->nr_ctx;
+ hctx->ctxs[hctx->nr_ctx++] = ctx;
+ }
+}
+
+struct request_queue *blk_mq_init_queue(struct blk_mq_reg *reg,
+ void *driver_data)
+{
+ struct blk_mq_hw_ctx **hctxs;
+ struct blk_mq_ctx *ctx;
+ struct request_queue *q;
+ int i;
+
+ if (!reg->nr_hw_queues ||
+ !reg->ops->queue_rq || !reg->ops->map_queue ||
+ !reg->ops->alloc_hctx || !reg->ops->free_hctx)
+ return ERR_PTR(-EINVAL);
+
+ if (!reg->queue_depth)
+ reg->queue_depth = BLK_MQ_MAX_DEPTH;
+ else if (reg->queue_depth > BLK_MQ_MAX_DEPTH) {
+ pr_err("blk-mq: queuedepth too large (%u)\n", reg->queue_depth);
+ reg->queue_depth = BLK_MQ_MAX_DEPTH;
+ }
+
+ if (reg->queue_depth < (reg->reserved_tags + BLK_MQ_TAG_MIN))
+ return ERR_PTR(-EINVAL);
+
+ ctx = alloc_percpu(struct blk_mq_ctx);
+ if (!ctx)
+ return ERR_PTR(-ENOMEM);
+
+ hctxs = kmalloc_node(reg->nr_hw_queues * sizeof(*hctxs), GFP_KERNEL,
+ reg->numa_node);
+
+ if (!hctxs)
+ goto err_percpu;
+
+ for (i = 0; i < reg->nr_hw_queues; i++) {
+ hctxs[i] = reg->ops->alloc_hctx(reg, i);
+ if (!hctxs[i])
+ goto err_hctxs;
+
+ hctxs[i]->numa_node = NUMA_NO_NODE;
+ hctxs[i]->queue_num = i;
+ }
+
+ q = blk_alloc_queue_node(GFP_KERNEL, reg->numa_node);
+ if (!q)
+ goto err_hctxs;
+
+ q->mq_map = blk_mq_make_queue_map(reg);
+ if (!q->mq_map)
+ goto err_map;
+
+ setup_timer(&q->timeout, blk_mq_rq_timer, (unsigned long) q);
+ blk_queue_rq_timeout(q, 30000);
+
+ q->nr_queues = nr_cpu_ids;
+ q->nr_hw_queues = reg->nr_hw_queues;
+
+ q->queue_ctx = ctx;
+ q->queue_hw_ctx = hctxs;
+
+ q->mq_ops = reg->ops;
+
+ blk_queue_make_request(q, blk_mq_make_request);
+ blk_queue_rq_timed_out(q, reg->ops->timeout);
+ if (reg->timeout)
+ blk_queue_rq_timeout(q, reg->timeout);
+
+ blk_mq_init_flush(q);
+ blk_mq_init_cpu_queues(q, reg->nr_hw_queues);
+
+ if (blk_mq_init_hw_queues(q, reg, driver_data))
+ goto err_hw;
+
+ blk_mq_map_swqueue(q);
+
+ mutex_lock(&all_q_mutex);
+ list_add_tail(&q->all_q_node, &all_q_list);
+ mutex_unlock(&all_q_mutex);
+
+ return q;
+err_hw:
+ kfree(q->mq_map);
+err_map:
+ blk_cleanup_queue(q);
+err_hctxs:
+ for (i = 0; i < reg->nr_hw_queues; i++) {
+ if (!hctxs[i])
+ break;
+ reg->ops->free_hctx(hctxs[i], i);
+ }
+ kfree(hctxs);
+err_percpu:
+ free_percpu(ctx);
+ return ERR_PTR(-ENOMEM);
+}
+EXPORT_SYMBOL(blk_mq_init_queue);
+
+void blk_mq_free_queue(struct request_queue *q)
+{
+ struct blk_mq_hw_ctx *hctx;
+ int i;
+
+ queue_for_each_hw_ctx(q, hctx, i) {
+ cancel_delayed_work_sync(&hctx->delayed_work);
+ kfree(hctx->ctx_map);
+ kfree(hctx->ctxs);
+ blk_mq_free_rq_map(hctx);
+ blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
+ if (q->mq_ops->exit_hctx)
+ q->mq_ops->exit_hctx(hctx, i);
+ q->mq_ops->free_hctx(hctx, i);
+ }
+
+ free_percpu(q->queue_ctx);
+ kfree(q->queue_hw_ctx);
+ kfree(q->mq_map);
+
+ q->queue_ctx = NULL;
+ q->queue_hw_ctx = NULL;
+ q->mq_map = NULL;
+
+ mutex_lock(&all_q_mutex);
+ list_del_init(&q->all_q_node);
+ mutex_unlock(&all_q_mutex);
+}
+EXPORT_SYMBOL(blk_mq_free_queue);
+
+/* Basically redo blk_mq_init_queue with queue frozen */
+static void __cpuinit blk_mq_queue_reinit(struct request_queue *q)
+{
+ blk_mq_freeze_queue(q);
+
+ blk_mq_update_queue_map(q->mq_map, q->nr_hw_queues);
+
+ /*
+ * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
+ * we should change hctx numa_node according to new topology (this
+ * involves free and re-allocate memory, worthy doing?)
+ */
+
+ blk_mq_map_swqueue(q);
+
+ blk_mq_unfreeze_queue(q);
+}
+
+static int __cpuinit blk_mq_queue_reinit_notify(struct notifier_block *nb,
+ unsigned long action, void *hcpu)
+{
+ struct request_queue *q;
+
+ /*
+ * Before new mapping is established, hotadded cpu might already start
+ * handling requests. This doesn't break anything as we map offline
+ * CPUs to first hardware queue. We will re-init queue below to get
+ * optimal settings.
+ */
+ if (action != CPU_DEAD && action != CPU_DEAD_FROZEN &&
+ action != CPU_ONLINE && action != CPU_ONLINE_FROZEN)
+ return NOTIFY_OK;
+
+ mutex_lock(&all_q_mutex);
+ list_for_each_entry(q, &all_q_list, all_q_node)
+ blk_mq_queue_reinit(q);
+ mutex_unlock(&all_q_mutex);
+ return NOTIFY_OK;
+}
+
+static int __init blk_mq_init(void)
+{
+ unsigned int i;
+
+ for_each_possible_cpu(i)
+ init_llist_head(&per_cpu(ipi_lists, i));
+
+ blk_mq_cpu_init();
+
+ /* Must be called after percpu_counter_hotcpu_callback() */
+ hotcpu_notifier(blk_mq_queue_reinit_notify, -10);
+
+ return 0;
+}
+subsys_initcall(blk_mq_init);
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.